The indirect attraction between holes in the extended hubbard model
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The extended Hubbard model [V. J. Emery,Phys. Rev. Lett.58, 2794 (1987)] is used to study the copper-oxide plane of the high-T c superconducting material. Due to the Coulomb repulsion between the holes on oxygen and copper atoms, there exists an indirect attraction between oxygen holes. Correlation among holes will enhance rather than screen the attraction. Calculation based on the Hartree-Fock and random-phase approximations show that it is quite large. A comparison with direct Coulomb repulsion shows that it is greater in a certain range of momentum transfer. It is sufficient to provide the pairing mechanism to give high critical temperature.
Key wordsHubbard Hamiltonian Coulomb interaction BCS model strong coupling
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References and Notes
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